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Method for controlling reticular carbide in bearing steel bar and device for implementing the method

A technology of reticulated carbide and control method, applied in the direction of temperature control, metal rolling, manufacturing tools, etc., can solve the problems of limited degree of carbide segregation, high energy consumption, burning loss of casting billet, etc. The formation of tissue, the simple cooling process, and the effect of improving product quality

Active Publication Date: 2017-10-31
SHANDONG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Usually, the continuous casting process is optimized, the heating furnace is used to perform long-term high-temperature diffusion annealing on the slab, and the content of alloying elements is controlled at the middle and lower limits to reduce the network carbide structure. However, the degree of carbide segregation is very limited in the continuous casting stage. Easy to cause slab burning, high energy consumption, not ideal
In some patents, water tanks are used to cool the bearing steel to control reticular carbides, but in the actual production process, the length of the continuous casting slab after rolling is between 40 and 60m, and the head and tail are seriously bent. The water tank is easy to get stuck in it, causing production accidents; if the water tank is entered after cutting the head and tail, the temperature of the rolled material will be greatly reduced, and the network carbide will have sufficient time to precipitate and form, and the effect will be greatly reduced
Therefore, the current bearing steel production process is difficult to meet the production requirements of high-quality bearing steel grades, and the bearing steel network carbides generally can only be controlled at about 2.5 grades using the traditional post-rolling cooling bed cooling process

Method used

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  • Method for controlling reticular carbide in bearing steel bar and device for implementing the method
  • Method for controlling reticular carbide in bearing steel bar and device for implementing the method

Examples

Experimental program
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Effect test

Embodiment 1

[0032] In this embodiment, the specification of the continuous casting slab is 180 mm×220 mm, and the rolling specification is Φ20 mm. The final rolling temperature is 940-980°C. first after rolling figure 1 After the shown cooling bed input roller table 1 reaches the receiving station of the cooling bed rapid water cooling zone 2, it is translated to the cooling bed rapid water cooling zone 2, and the cooling water in the cooling water pipe 6 performs forced rapid water cooling on the bearing steel bar 5 (Rapid water cooling from 940 to 980°C to 400 to 450°C can effectively suppress the precipitation of network carbides at the austenite grain boundaries), the cooling rate is about 40°C / S, and the water cooling time is about 13s until the surface temperature of the bearing steel reaches 400~ After 450°C, the temperature sensor on the rapid water cooling zone 2 of the cooling bed receives the temperature signal and transmits the temperature signal to the control system. Go to...

Embodiment 2

[0034] In this embodiment, the specification of the continuous casting slab is 180 mm×220 mm, and the rolling specification is Φ40 mm. The final rolling temperature is 950-990°C. first after rolling figure 1After the shown cooling bed input roller table 1 reaches the receiving station of the cooling bed rapid water cooling zone 2, it is translated to the cooling bed rapid water cooling zone 2, and the cooling water in the cooling water pipe 6 performs forced rapid water cooling on the bearing steel bar 5 (Rapid water cooling from 950 to 990°C to 400 to 450°C can effectively suppress the precipitation of network carbides at austenite grain boundaries), the cooling rate is about 35°C / S, and the water cooling time is about 16s until the surface temperature of the bearing steel reaches 400~ After 450°C, the temperature sensor on the rapid water cooling zone 2 of the cooling bed receives the temperature signal and transmits the temperature signal to the control system. Go to the ...

Embodiment 3

[0036] In this embodiment, the specification of the continuous casting slab is 180 mm×220 mm, and the rolling specification is Φ60 mm. The final rolling temperature is 960~1000℃. first after rolling figure 1 After the shown cooling bed input roller table 1 reaches the receiving station of the cooling bed rapid water cooling zone 2, it is translated to the cooling bed rapid water cooling zone 2, and the cooling water in the cooling water pipe 6 performs forced rapid water cooling on the bearing steel bar 5 (Rapid water cooling from 960~1000℃ to 400~450℃ can effectively suppress the precipitation of network carbides at the austenite grain boundary), the cooling rate is about 30℃ / S, and the water cooling time is about 20s until the surface temperature of the bearing steel reaches 400~ After 450°C, the temperature sensor on the rapid water cooling zone 2 of the cooling bed receives the temperature signal and transmits the temperature signal to the control system. Go to the slow ...

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Abstract

The invention discloses a control method for bearing steel bar network carbide and a device for implementing the method. The control method comprises the following steps that the finish rolling temperature of a bearing steel bar with the diameter being phi 20-60 mm is controlled to be 940-1000 DEG C, and the cooling speed of the bearing steel bar is controlled through a double-cooling-area cooling mode after rolling; double cooling areas include the cooling bed quick water cooling area and the cooling bed re-reddening slow cooling area; during the process in the cooling bed quick water cooling area, after rolling, the high-temperature bearing steel bar is fed into the cooling bed quick water cooling area from a cooling bed entry table, and the surface temperature of the bearing steel bar is controlled to be rapidly decreased to 400-450 DEG C through water cooling; during the process in the cooling bed re-reddening slow cooling area, when the temperature of the core part of the bearing steel bar fed into the re-reddening slow cooling area is higher than the surface temperature, heat diffuses from interior to exterior, the bearing steel bar starts to re-redden, the surface temperature is raised to 600-650 DEG C, and then the bearing steel bar is slowly cooled to 150-300 DEG C in the air. The structure grade of the network carbide is controlled within the 1.0 grade.

Description

technical field [0001] The invention belongs to the field of production and manufacture of bearing steel products. Specifically, the invention relates to a method for controlling reticular carbides in bearing steel rods and a device for implementing the method. Background technique [0002] Bearing steel is the steel used to manufacture bearing rollers, balls and bearing rings. Its quality requirements are high, and it has high requirements on indicators such as gas content and carbide distribution uniformity. Bearing steel belongs to hypereutectoid steel. During the cooling process after hot rolling, due to the decrease of the solubility of carbon in austenite, supersaturated carbide precipitates along the austenite grain boundary network, and the presence of network carbide increases. The brittleness of steel reduces the ability of the material to withstand impact loads and affects the service life of the bearing. [0003] Due to the high content of carbon and chromium in...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B21B37/76B21B43/00C21D8/06
CPCB21B37/76B21B43/00C21D8/065
Inventor 李金浩戈文英刘兵梁娜袁淑君欧阳峥荣
Owner SHANDONG IRON & STEEL CO LTD
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